Polarizing lenses are widely used for sunglasses or goggles because of excellent anti-glare properties. As polarizing films to be used for polarizing lenses, those obtained by staining a polymer film made of polyvinyl alcohol or a derivative thereof with a dichroism pigment such as iodine and an azo dye and subjecting it to orientation by means of uniaxial stretching are used.
A transparent protection sheet is bonded to both the surfaces of such a polarizing film to produce a polarizing sheet, and then it is subjected to a curving process to provide a curved polarizing lens. In the case of polarizing lenses particularly requiring impact resistance and heat resistance, a polycarbonate-based resin sheet is used as a protection sheet (Patent Document 1).
Further, for the purpose of further improving impact resistance or providing a lens for vision correction, injected polarized lenses obtained by lining the polarizing sheet with a polycarbonate-based resin by means of injection molding after the curving process are also widely used (Patent Document 2).
Further, imparting design property to lenses is generally carried out, and sunglasses in which gradation is applied to lenses and sunglasses in which surfaces of lenses are mirrored are commercially available.
In the case of mirror coating, there is a problem that light incident on the face from the outside of the lens or through the lens is reflected from the face and further reflected from the mirror coating to easily cause the appearance of reflections.
For the purpose of reducing the appearance of reflections, methods in which a dielectric membrane having a high light absorption coefficient is laminated on the back surface side of a reflection layer (Patent Document 3) or a base material of lenses is colored (Patent Document 4) are disclosed.
However, since a high light absorption rate in the dielectric membrane or light absorption layer is required in order to suppress the appearance of reflections, there is a problem that light transmitted through the lens is reduced. Moreover, when the transmittance of the lens is increased, there is a problem that the appearance of reflections cannot be completely suppressed.
Further, by adjusting the refraction index and film thickness of each layer of a dielectric multi-layer film, a mirror coating, in which the reflection rate at a specific wavelength is increased to provide a reflected color having a high color purity, and which provides a variety of colors, has been obtained (Patent Document 4).
However, when the color purity of the reflected color is increased, the wavelength component of the transmitted light is decreased, and therefore there is a problem of reduction in visibility. For correcting the wavelength component, a method for coloring a base material for lenses is disclosed (Patent Document 4). However, in methods for correcting a wavelength component by means of absorption such as coloring a base material for lenses, there is a problem that the transmittance of lenses is reduced by strong color correction. Moreover, when the transmittance of lenses is increased, there is a problem that sufficient color correction cannot be obtained.